Ragwort poisoning is the most common cause of liver damage in horses in the U.K. The plant Senecio jacobeais a hardy biennial. It flourishes in waste ground and roadside verges from where it invades nearby fields. The growing plant is not palatable to grazing animals and is usually ignored by horses, except when the grass is extremely poor. It thus has a competitive advantage over the other plants (including grass) and fields quickly become heavily contaminated.
Ragwort is a common weed in waste ground and roadside verges.
An important feature of the plants’ life cycle is that it is biennial. During the first year the plant produces only roots, a short stem and leaves.
During its first year the plant is a flat rosette.
This means that mowing or cutting during its first year of growth does not damage it.
The plant has a long flowering period from May to Sept during which the characteristic small yellow flowers make the plant easily detectable.
During its second year the plant develops a tall stem and has small yellow flowers.
As stated above horses will not usually eat the living plant. However ragwort becomes more palatable and therefore a significant risk to horses after it has died and wilted, either at the end of its second year or after moving or cutting pasture for hay. Hay from ragwort contaminated fields is thus an important cause of ragwort poisoning.
The plant can be removed from fields by the use of broadleaf herbicides or by pulling them up and burning. It will take a number of years to eliminate the plant completely. Simply mowing the fields is dangerous to horses as it contaminates the pasture with wilted plants.
The level of Ragwort exposure required to produce the disease is not known. Consuming up to 5% of body weight can produce acute toxicity, but it is more common for horses to experience long term low level exposure in hay. The effects of the ragwort become cumulative causing liver malfunction over a period of months.
Symptoms include: –
- Weight loss, depression, decreased appetite, neurological signs (yawning, head pressing, and ataxia). Swelling under the abdomen (ventral oedema), photosensitization and jaundice may also be present. Many horses die within two to four weeks of initial presentation.
The disease can be confirmed by your Vet in two ways. A blood test for specific liver enzymes (GGT and ALP) is the most usual, in cases where doubt arises a liver biopsy can be performed.
Once actual symptoms have developed, especially any neurological symptoms, the prognosis is poor, however in the early stages careful dietary control and vitamin supplementation can be helpful.
- Avoid most cereals (barley, wheat and oats
- Avoid early cut hay
- Avoid clover or alfalfa hay
- Feed oat hay ad lib or feed meadow hay ad lib.Low protein
- High carbohydrate
- Feed molassed sugar beet pulp plus maize (2:1 ratio) little and often to appetite at a rate of up to 2 kg/100 kg body weight.
- Supplement vitamins A,D,E, and B12.